Where does Bypass valve air return to
10-11-2009, 09:16 PM
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Where does Bypass valve air return to
I have spent hours looking for a diagram so i didn't have to ask this question .....but couldn't find **** on our turbo . So my question is this ........Where does the bypassed air from our bypass valve go when it recirculates? Maybe i've been looking to hard for something right in front of me but ......Its driving me crazy no being able to figure out where the bypassed air is routed . Thanks for any info.
10-11-2009, 09:46 PM
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I thought that too but after looking at the routing of the breather line that connects between the air box and the turbo.......that line runs from the valve cover . Would they release the pressure into the valve cover and back out to the intake?
10-12-2009, 03:04 AM
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who'da thunk a spare turbo would come in handy so much, lol:
This is the uncompressed side of the turbo. Here you can see the holes from the BPV, and the line that goes to the valve cover.
And this is the compressed side of the turbo. Here you can see the hole that leads the air through the bypass valve, showing that it is obviously internally routed.
As for what the line does exactly, and which way it flows... I haven't a clue. I am still trying to dig and find it.
10-12-2009, 03:10 AM
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It is actually routed right to the before the intake side of the compressor wheel. And, the line that goes to the valve cover is also right before the intake side of the compressor wheel. I am not sure if the air vents back to the valve cover from the turbo or not. BUT, I did notice that once when i had the fitting off the intake (when I broke the little nipple), there was an arrow pointing AWAY from the intake toward the valve cover, and on that fitting is a little check valve. It seems that it only wants to allow air to go TO the valve cover...
who'da thunk a spare turbo would come in handy so much, lol:
This is the uncompressed side of the turbo. Here you can see the holes from the BPV, and the line that goes to the valve cover.
And this is the compressed side of the turbo. Here you can see the hole that leads the air through the bypass valve, showing that it is obviously internally routed.
As for what the line does exactly, and which way it flows... I haven't a clue. I am still trying to dig and find it.
who'da thunk a spare turbo would come in handy so much, lol:
This is the uncompressed side of the turbo. Here you can see the holes from the BPV, and the line that goes to the valve cover.
And this is the compressed side of the turbo. Here you can see the hole that leads the air through the bypass valve, showing that it is obviously internally routed.
As for what the line does exactly, and which way it flows... I haven't a clue. I am still trying to dig and find it.
omg this is awsome news...keep us updated
10-12-2009, 03:11 AM
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OMG, please edit the pics out of your quote.
And yes, I will. If I had a couple wrenches in my bedroom, I would take off the cover to the BPV, but I am supposed to be doing homework, lol.
And yes, I will. If I had a couple wrenches in my bedroom, I would take off the cover to the BPV, but I am supposed to be doing homework, lol.
10-12-2009, 12:46 PM
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It is actually routed right to the before the intake side of the compressor wheel. And, the line that goes to the valve cover is also right before the intake side of the compressor wheel. I am not sure if the air vents back to the valve cover from the turbo or not. BUT, I did notice that once when i had the fitting off the intake (when I broke the little nipple), there was an arrow pointing AWAY from the intake toward the valve cover, and on that fitting is a little check valve. It seems that it only wants to allow air to go TO the valve cover...
who'da thunk a spare turbo would come in handy so much, lol:
This is the uncompressed side of the turbo. Here you can see the holes from the BPV, and the line that goes to the valve cover.
And this is the compressed side of the turbo. Here you can see the hole that leads the air through the bypass valve, showing that it is obviously internally routed.
As for what the line does exactly, and which way it flows... I haven't a clue. I am still trying to dig and find it.
who'da thunk a spare turbo would come in handy so much, lol:
This is the uncompressed side of the turbo. Here you can see the holes from the BPV, and the line that goes to the valve cover.
And this is the compressed side of the turbo. Here you can see the hole that leads the air through the bypass valve, showing that it is obviously internally routed.
As for what the line does exactly, and which way it flows... I haven't a clue. I am still trying to dig and find it.
10-12-2009, 11:30 PM
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After looking at your pic's and the GM drawing ......It must blow off into the Valve Cover (camshaft cover ) ..... then it flows back out another PCV line back into the intake. I'm really surprised by that .
Now someone who is brave needs to route it direct from the turbo to the intake lol. I really have no idea what would happen to the rest of the pcv system thou .
Last edited by rukkee; 10-13-2009 at 12:14 AM.
10-13-2009, 12:16 AM
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If you look under that little yellow piece where the vacum line goes in you can see the route the air takes when the bypass valve opens. Those are good pictures. I wounder if there is any possible gains from porting our factory turbo??? that thing has some pretty small inlet and outlet holes... and not very aerodynamic or flow worthy designed
The above is not how it works
It is directly shot back into your air intake before the turbo. Like i said above if you remove the yellow cover where the vacume line goes in you will pull out the BPV. it will have a litttle spring and plunger type piece. then you can see where the air runs back into the intake/pre turbo. the air actually blows back out your air filter. thats why our BPVs are so quiet on out cars. The valve just releases the pressure in the piping into your air intake.
The above is not how it works
It is directly shot back into your air intake before the turbo. Like i said above if you remove the yellow cover where the vacume line goes in you will pull out the BPV. it will have a litttle spring and plunger type piece. then you can see where the air runs back into the intake/pre turbo. the air actually blows back out your air filter. thats why our BPVs are so quiet on out cars. The valve just releases the pressure in the piping into your air intake.
10-13-2009, 12:37 AM
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What silverbullet said, it just shoots the metered air back into the turbos inlet. Billion cars out there with release valves built onto the compressor housing like this 
Car just happens to have two PCV valve cover breathers, one with a check valve and one without. The one without is close to the release valve port for packaging reasons. That is also another common feature of most turbocharged vehicles.
Not worth posting, but just hit google and start reseaching PCV systems for turbocharged cars and it'll all make sense why they're configured like that.
Car just happens to have two PCV valve cover breathers, one with a check valve and one without. The one without is close to the release valve port for packaging reasons. That is also another common feature of most turbocharged vehicles.
Not worth posting, but just hit google and start reseaching PCV systems for turbocharged cars and it'll all make sense why they're configured like that.
10-13-2009, 01:26 AM
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Yah, thats normal PCV routing. The hose off the turbo is the fresh air supply, the one going to the intake tube with the check valve is the blow-by. Good diagram though, I'll shuffle that into my gallery. The BPV isnt the source of the fresh air though, its drawn in on its own. You wouldnt want to force pressure into the PCV system, because then you'd have a lot of fun keeping oil behind the seals and would negate the entire purpose of trying to relieve POSITIVE crank case pressure (thus the name).
and would negate the entire purpose of trying to relieve POSITIVE crank case pressure (thus the name).
10-13-2009, 01:31 AM
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Yah, thats normal PCV routing. The hose off the turbo is the fresh air supply, the one going to the intake tube with the check valve is the blow-by. Good diagram though, I'll shuffle that into my gallery. The BPV isnt the source of the fresh air though, its drawn in on its own. You wouldnt want to force pressure into the PCV system, because then you'd have a lot of fun keeping oil behind the seals and would negate the entire purpose of trying to relieve POSITIVE crank case pressure (thus the name).
and would negate the entire purpose of trying to relieve POSITIVE crank case pressure (thus the name).
10-13-2009, 01:37 AM
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10-13-2009, 04:06 AM
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ok maybe this is a dumb question, but wouldn't it be difficult for the fresh air source to be supplied from the line that close to the compressor inlet? there's an awfull lot of negative pressure and air velocity that close to the wheel. even when not under boost, it seems to me there would be too much air flow running past the pvc opening to encourage much air flow. unless the valve train somehow pulls air through. just wondering out loud. its obvious by the GM diagram that's how it works 
10-13-2009, 04:09 AM
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This is speculation... but I think that if the crankcase build a negative pressure, it gets its air from the line that goes to the turbo, and if it builds a positive pressure, it sends the air back to the intake. Sounds about right in my head.
Now, what would happen if we put a big turbo on? Do all turbos have PCV line outlets?
Now, what would happen if we put a big turbo on? Do all turbos have PCV line outlets?
10-13-2009, 09:35 AM
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